1. Field of Invention
This invention relates to a screw driver, more particularly to one having an illuminating means mounted thereto so that such a screw driver is capable of operating in darkness, as well as in day light.
2. Description of the Related Art
A screw driver is a very useful tool applicable in various fields, such as in repairing operation and the like. It is a well known fact that it is not a problem to use a screw driver in the day time, but while working at night or in darkness it is not possible to see an object on which the screw driver is working. Holding a torch in one hand while the remaining hand working with a screw driver is very inconvenient and cumbersome for an operator.
There already exists a screw driver having an illuminating unit fixedly attached at a front portion of the handle of the screw driver. Though such a screw driver can offer some light, it can only cover a limited range because the illuminating unit is fixed to the front of the handle while the working tip is still a distance away therefrom. The shank by itself can cause a shadow over a workpiece, i.e. a screw or can at least reduce the clear visibility of the workpiece. Therefore, in order to provide clear visibility, the length of the shank of the screw driver must be taken into consideration. The shank of such screw driver is generally made very short in order to overcome said drawback. When the shank is shortened, it is not applicable in some cases, for example, when it is necessary to screw at the bottom of a bore deeper than the length of the shank of the driver.
There is still another kind of screw driver, which having a light reflective means mounted right beside the illuminating unit which can convey rays of light to the tip of the screw driver so that one can se the working spot clearer. Though the above-mentioned drawback is somewhat solved by this screw driver construction but the installation of the reflective means has a greater cost and the limited length of the shank is not fully solved.